The Bruins are clear about five of their seven defensemen. Zdeno Chara is their shutdown ace. Johnny Boychuk is the hard-hitting first- or second-pairing strongman. Torey Krug is the power-play specialist. Kevan Miller is the No. 6 stay-at-homer. Adam McQuaid is the one who can’t stay healthy.

There is less definition regarding Dougie Hamilton and Matt Bartkowski. It is because their ceilings correspond with their skill.

Whether using their wheels or sticks, Hamilton and Bartkowski can be the team’s best at pushing the pace and moving the puck. At their peak, which they showed in Saturday’s 4-0 win over the JV Oilers at TD Garden, Hamilton and Bartkowski can change the game.

When they’re off, their shortcomings — Hamilton’s inexperience, Bartkowski’s decision-making — can show up on the scoreboard. The Bruins have until March 5 to determine if they’re willing to accept the young defensemen’s risks or their rewards.

Less than a year ago, Hamilton was the odd man out to start the playoffs. The Bruins were set on the right side with Dennis Seidenberg, Boychuk, and McQuaid. Now, the second-year pro is the leader in the team’s audition to determine Chara’s playoff partner.

Against the Oilers, Hamilton logged 18:49 of ice time. Chara and Hamilton took shifts against Edmonton’s top line of Taylor Hall, Ryan Nugent-Hopkins, and Jordan Eberle. None of the three forwards scored, mostly because the sad-sack Oilers never controlled the puck.

“Just trying to play tough and limit their opportunities,” Hamilton said. “I know every line that I play against, if you make a mistake, they can score. It’s defense first. That’s it.”

Hamilton could develop into a shutdown presence. The 6-foot-5-inch, 212-pound Hamilton is still growing. He has an active stick and is a good enough skater to tighten gaps quickly and recover when he’s out of position.

Right now, the 20-year-old’s best asset is his offensive bent. After two periods, the Bruins were dominating the game. They claimed the puck as their own. The Oilers never had any offensive presence. But because of their bad aim and goalie Ben Scrivens’s solid play, the Bruins were only up, 1-0.

Hamilton changed that in the third.

With help from Loui Eriksson’s neutral-zone pick on Nail Yakupov, Hamilton breezed into the offensive zone and put a soft shot on goal from the right circle. Scrivens sticked away the shot, but steered the puck right back toward Hamilton. The defenseman whipped around the net and flipped the puck on goal. The puck bounced off Scrivens’s right pad and over the line at 6:43, giving the Bruins a 2-0 lead.

The Oilers never pushed back.

“They picked the right time to go,” coach Claude Julien said of Hamilton and Bartkowski. “That’s what I liked about them pushing the pace. In Dougie’s case, carrying that puck when he did on that goal was the right time. Not only that, but he stayed on the puck and was allowed to get a second chance at it.”

It was Hamilton’s second goal in the last two games. Against Montreal on Thursday, Hamilton ripped a shot from the point that deflected off Andrei Markov and past Peter Budaj. Hamilton now has a career-high six goals this season. He’s taking advantage of his better-than-average legs.

“I think we’ve got good skating defensemen that are all two-way,” Hamilton said. “It’s pretty tough to defend against when other teams have to play against that. I think when we move the puck and we move our feet, we’re better as a team and we get the puck out of our end a lot better.”

Unlike last year, Hamilton is a lock to play in the postseason. Bartkowski’s odds are not as airtight.

Chara is the No. 1 left-shot defenseman. Krug hasn’t skated as well lately, and his size makes him a liability against bigger forwards. But Krug is locked in to the left side on the third duo because of his power-play presence.

For now, Bartkowski is the left-side man on the second pairing. He will move to the first when Chara takes his two-game flag-bearing leave of absence against St. Louis and Ottawa.

But if the Bruins acquire a left-shot defenseman, Bartkowski could be in the press box to start the playoffs. Chara and Krug are going nowhere.

Bartkowski is trying to make that a hard decision. In 18:39 of playing time, Bartkowski recorded one assist and had another taken away.

In the second, Bartkowski crossed the offensive blue line and picked his way around David Perron. By eluding Perron, Bartkowski opened up options to shoot or find someone in front. Bartkowski went with the latter when he spotted Eriksson. Bartkowski slipped the puck under Sam Gagner toward Eriksson, who appeared to give the Bruins a 2-0 lead. Video review concluded Eriksson had made a distinct kicking motion.

“Bringing the puck to an area where he could throw it to the front of the net, those are all things that I think our young guys are getting better at,” Julien said.

Left-shot defensemen such as Andrew MacDonald, Henrik Tallinder, and Chris Phillips are rentals the Bruins would consider. Few teams in the playoff hunt are eager to add term beyond this season. As such, those defensemen would come at a high cost.

The Bruins still need blue-line help. Injuries will happen. But if Hamilton and Bartkowski maximize their strengths and minimize their mistakes, the Bruins will be cautious about giving up too much. They are in no hurry to get ripped off.